[R] in R when I get negative adjusted R^2 using "lm", what might be the problem?

[Michael]

This is a linear regression of Y onto factors...

If I take log of Y, and regress onto the factors, I got:

Multiple R-squared: 0.4023,     Adjusted R-squared: 0.2731

If I don't take log of Y, and directly regress Y onto the factors, I got:

Multiple R-squared: 0.1807,     Adjusted R-squared: -0.001112

Is this negative adjusted R^2 a problem?

What observation can I make here and what might be the problem?

Thanks!